Device-to-Device (D2D) discovery is a process of determining whether a user equipment (UE) that is capable of D2D communication (hereinafter, referred to as D2D-enabled UE) is in proximity of another D2D-enabled UE. Discovery of a D2D-enabled UE comprises determining whether another D2D-enabled UE is of interest to it using D2D discovery. A D2D-enabled UE is of interest to a discovering D2D-enabled UE if its proximity needs to be known by one or more authorized applications in the discovering D2D-enabled UE.
For example, a social networking application may be enabled to use D2D discovery features. The D2D discovery enables the D2D-enabled UE of a given user of a social networking application to discover and be discoverable by the D2D-enabled UEs of his/her friends. In another example, the D2D discovery may enable the D2D-enabled UE of a given user of a search application to discover stores or restaurants of interest in its proximity.
A D2D-enabled UE may discover other D2D-enabled UEs in its proximity by using direct UE-to-UE signaling with evolved universal terrestrial radio access (E-UTRA) technology. This is referred as D2D direct discovery. Alternatively, a communication network determines the proximity of two D2D-enabled UEs and informs them of their proximity. This is referred as network-assisted D2D discovery.
It is assumed that the same spectrum or radio frequency is used for D2D discovery and regular communication between a UE and a base station (BS). In traditional communication, a UE and a BS communicate with each other by establishing a connection with each other and the BS allocates dedicated resources to the UE.
In the case of D2D discovery, the requirements are quite different. There is no one-to-one communication between a D2D-enabled UE transmitting discovery information and another D2D-enabled UE receiving the discovery information during D2D direct Discovery. The discovery information transmitted by the D2D-enabled UE may be received and processed by multiple D2D-enabled UEs. D2D discovery is a continuous process performed by the D2D-enabled UEs. The D2D-enabled UEs should be able to perform D2D discovery irrespective of their states (that is, idle or connected). During the D2D direct discovery, the D2D-enabled UE monitoring the discovery information should know time and frequency resources used by the D2D-enabled UE transmitting the discovery information. The D2D discovery should coexist with legacy UE-BS communication. The time and frequency resources configured for discovery should minimize impact on legacy UEs. For example, latency-sensitive applications of legacy UEs should not be affected. That is, a synchronous hybrid automatic repeat request (HARQ) operation on an uplink (UL) should not be affected.
Accordingly, there is a need for a method for configuring and signaling resources for D2D discovery.
The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present disclosure.